*4.1. Satellite-Image-Classification-Based Method and Classification Accuracy*

In this study, the accuracy of most images can reach a threshold of above 90%. Although some of the user and producer accuracies are lower than 80%, most have an accuracy between 81.3% and 99.5%, and such an accuracy threshold is deemed satisfactory for the studied area with complex and diverse land features categories [51].

#### *4.2. The Formation and Distribution Mechanism of PLES from the Geomorphic Perspective*

The PLES diversity in the studied area is closely related to island sizes. Usually, islands with a larger area have relatively complete geomorphic combinations with more developable geomorphic types [52]. This kind of island has more diversified PLES. In contrast, the landform of small islands is unitary. Some small bedrock islands only have hills and sandy beaches. Thus, the exploitation extent is limited, with less PLES (Table 5). Furthermore, the geomorphology of islands also influences the development level, dominant space, and distribution characteristics. According to the concept and method of Geomorphons [53], the geomorphic elements were extracted from DEM data by ArcGIS, and the PLES of different islands was analyzed in this study.
